Depending on the model of the truck, the alternator is on the back side of the engine and can only be reached through the passenger fender well if your Y Pipe is from 2005 or earlier model or if it is from 2006 and later models the alternator is on the front side. It is almost impossible to get to these models especially when you need to repair the alternator, you might have to remove some of the following parts, the Engine Cooling Fan according to some models. To start with, this is by pulling the cable connecting it to the negative terminal of the battery. Subsequently, if required, take off the engine cover as well as the drivebelt of the vehicle. Undo electrical connections from the alternator, the next step is to remove the top bolt with its nut and washer and the bottom bolt for the later models and it is similar for the previous modes. If you are swapping your alternator, bring the old one with you when going to the store, new or rebuilt alternator should be the same with the terminal number, size, and position as well as the identification marks. If the new alternator that you are going to install does not already have a pulley, you may have to steal the one from the old alternator and ask the shop about this service. Installation is done in the reverse sequence that was followed during removal and after that confirm charging voltage for efficiency of the alternator.